OBJECTIVES: To determine the short-term impact of a soft opt-out organ donation system on consent rates and donor numbers.

DESIGN: Before and after observational study using bespoke routinely collected data.

SETTING: National Health Service Blood and Transplant.

PARTICIPANTS: 205 potential organ donor cases in Wales.

INTERVENTIONS: The Act and implementation strategy.

PRIMARY AND SECONDARY OUTCOMES: Consent rates at 18 months post implementation compared with 3 previous years, and organ donor numbers 21 months before and after implementation. Changes in organ donor register activity post implementation for 18 months.

RESULTS: The consent rate for all modes of consent was 61.0% (125/205), showing a recovery from the dip to 45.8% in 2014/2015. 22.4% (46/205) were deemed consented donors: consent rate 60.8% (28/46). Compared with the 3 years before the switch there was a significant difference in Welsh consent rates (χ2 p value=0.009). Over the same time period, rest of the UK consent rates also significantly increased from 58.6% (5256/8969) to 63.1% (2913/4614) (χ2 p value<0.0001), therefore the Wales increase cannot be attributed to the Welsh legislation change. Deceased donors did not increase: 101 compared with 104. Organ donation registration increased from 34% to 38% with 6% registering to opt-out.

CONCLUSION: This is the first rigorous initial evaluation with bespoke data collected on all cases. The longer-term impact on consent rates and donor numbers is unclear. Concerns about a potential backlash and mass opting out were not realised. The move to a soft opt-out system has not resulted in a step change in organ donation behaviour, but can be seen as the first step of a longer journey. Policymakers should not assume that soft opt-out systems by themselves simply need more time to have a meaningful effect. Ongoing interventions to further enhance implementation and the public's understanding of organ donation are needed to reach the 2020 target of 80% consent rates. Further longitudinal monitoring is required.